Mechanical furnace



Nov. 27, 1928.

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INVENTOR.

Otto H. Buse Patented Nov. 27, 1928.

UNITED STATES PATENT OFFICE.

OTTO H. BUSE, OF SHAKER HEIGHTS, OHIO, ASSIGNOB TO THE GRASSELLI CHEMICAL COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

MECHANICAL FURNACE.

Original application filed July 5, 1922, Serial No. 573,026, now Patent No. 1,561,054. Divided and this application filed October 13, 1925. Serial No. 62,290.

The present invention relates to a new and improved completely mechanical double stage furnace of the type widely-used in the manufacture of muriatic or hydrochloric acid and other chemicals, in which the materials are first charged onto a furnace floor where they are heated, during which action the material has to be stirred or agitated at intervals to break it up and to allow for the complete reaction that is to be carried out.

The present invention constitutes a division of the invention described and claimed in my co-pending application, Scr. No. 573,026, filed July 5, 1922, now Patent No. 1,561.054, and

relates particularly to improvements in the construction of a material loading or charging pot as used in connection with a. double stage furnace. To the accomplishment of the foregoing and related ends said invention,

then, consists of the means hereinafter fully described and particularly pointed out in the claims.

The annexed drawings and the following description set forth in detail certain mechanism embodying the invention, such disclosed means constituting, however, but one of various mechanical forms in which the principle of the invention may be used.

In said annexed drawings Fig. 1 is a longitudinal vertical section through a furnace for use with which my present invention is adapted Fig. 2 is a transverse vertical section through the charging pot and furnace and Fig. 3 is a greatlyenlarged sectional view of certain novel features of the present invention.

In the ordinary double-stage muriatic or hydrochloric acid furnace the salt is first shoveled into the pot by hand, the pot being adjacent to the mufliing furnace and being separate from it. The acid or sodium bisulphate, or a mixture of the two, is then run into the pot and after this pasty mass is heated and thickened, the material is pushed out of the pot into the mufile or furnace, this operation being carried out by hand with the use of long, heavy scrapers, which are extremely diflicult to handle. After the material is pushed into the furnace proper, it

, mustbe spread also by hand and then sliced off the hearth of the furnace, onto which it bakes after being first heated, and must therefore be turned over at regular intervals until the chlorine content of the mass has been reduced to the proper point, and sodium sulphate of the desired degreeof purity is obtained.

Such furnaces are commonly 16 to 22 feet long and from 6 to 8 feet wide inside, and the temperature which is maintained varies from 1200 to 1400 degrees F. The working of the material, that is, the charging, leveling, slic- 111 and removing, must be carried out by hand, and the tools used'must be of sufiicient length to reach to all points of the furnace. The result is that the tools used are extremely heavy and diflicult to handle and for proper operation of the furnace more or less skilled operators are required.

The present furnace has been designed to eliminate all of this heavy hand work without the use of mechanical graveling or stirring devices, which are used in all of the mechanical furnaces which have appeared on the market up to the present time, which have the disadvantage of requiring iron or steel in the furnace chamber. The weak point of all mechanical furnaces which employ metal in the furnace chamber proper has been the inability of the metal to stand up continuously under the temperature conditions which are required in the hydrochloric acid atmosphere. A further disadvantage of such furnaces has been their inability to employ the doublestage operation and at the same time produce satisfactory sulphate of soda.

In Fig. 1 there is shown a furnace in which there is a heating floor 1 which is heated by flues 2 and 3 above and below chamber 4:. The materialis charged onto this floor from a pot 5 which is mounted above the furnace and is connected thereto by means of a vertical conduit 6 which may be closed by means of a damper valve ,7 during the operation of the furnace. The novel mounting of the pot in the present furnace directly above the furnace proper allows for a gravity discharge of the material from the pot directly into the furnace, and also permits of the use of the waste heat from the furnace proper for heating the material in the pot, as will be explained hereinafter. Salt is first introduced to the pot, after which sulphuric acid or sodium bisulphate or a mixture of the two is charged in sufiicient quantity to combine with the salt to produce sodium/sulphate and able storage tanks and bins and during the flow of this material from the pot 5 into the chute 8 the material may be agitated by means of suitable scrapers 9, mounted in the bottom of the pot on the lower end of a rotatable shaft 10. A plug valve 11 is seated in an opening 12 in the bottom of the pot 5 and this plug seals this opening except during the charging operation. The plug 11 is formed of fire-brick and is sealed against the valve seat in the opening 12 by pouring a .small amount of acid resisting material around the top of the plug-in the recess formed at the point 13 between the upper beveled surface of the plug and the tapered side wall of the opening. Theplug may be removed or lifted from its seat'when it is desired to charge the furnace by a rod 14: passing through the shaft 10.

The furnace chamber 4 on the floor 1 of which the material is spread as it is charged through the conduit 6 is provided with a series of lateral openings 15 for the discharge of the gas.

The furnaceis heated bymeans of a fire box 90, or other equivalent means, the hot gases passing over the furnace through a passage 91, and then laterally through passages 92 and downward to a passage 93 beneath the hearth of the furnace. A portion of the gas is withdrawn through a port 94 and is passed upwardly through a conduit 95, and then through chambers 96 and 97 in the base of the pot for heating the contents thereof, this gas then being carried to astack 98. It is unnecessary to describe the construction of the furnace proper in detail or its operation since furnaces of this same general type are in common use and since the present invention may equally well be applied to furnaces of somewhat different construction and use.

The present furnace has several distinct advantages over the two-stage mechanical furnace now in use, ,or the two-stage hand furnaces which are the standard typefor the manufacture of the material in question. The present furnace allows the crude materials to be charged directly into the pot, eliminating all hand labor which. was formerly connected with this operation, and at the same time making the charging operation very much faster than has heretofore been possible. The pot discharges from a central opening, and the interior of the pot is readily accessible for cleaning. Heretofore a central gravity discharge from the pot has been considered impossible because of the difficulties of sealing the discharge opening during the first stage of the operation,

but this has been satisfactorily accomplished by means of the plug and sealing means already described. tents of the pot by gravity onto the hearth of the furnace facilitates the even distribution of the material over the hearth by the mechanical stirring and handling tools de scribed in the said Patent No. 1,561,054, and

the latter are operated very much faster, and of course with very much less labor than is possible with hand tools. Furthermore, the tools themselves are in the furnace atmosphere a very much shorter period because of the greater amount of work which can be done by the mechanically operated mechanis'm than can be done by hand labor in the same period. This decreases very materially the iron content of the finished sodium sulphate, since there is no contamination from the stirring mechanism.

Because of the absence of iron in the furnace it is possible to operate it at a higher temperature than is possible with mechanical furnaces containing iron stirrers or hearths, and this gives a salt cake of a very much higher degree of purity, the cake being practically free from excess sulphuric acid and from undecomposed salt.

Other modes of applying the principle of my invention may be employed instead of the oneexplained, change being made as regards the mechanism herein disclosed, provided the means stated by any of the following claims or the equivalent of such stated means be employed. 1

I therefore particularly point out and dis tinctly claim as my invention 1. In a two stage mechanical furnace, the combination of a charging pot, a furnace chamber below said pot, means for stirring material in said pot, an opening to allow gravity discharge of materials from said pot, and a removable plug closing such opening, a sealing groove being formed between the plug and the wall of the opening in the closed posltion 0f the plug.

2. In a two stage mechanical furnace, the combination of a charging pot, a furnace chamber below said pot, means for stirring material in said pot, an opening placing said furnace in communication with'said pot to allow gravity discharge of materials from said pot into said furnace, a removable plug closing such opening, a sealing groove being formed between the plug and the wall of the opening in the closed position of the plug, and means for directing heat from said furnace about said pot to heat the same.

3. In a two stage mechanical furnace, the combination of a charging pot, a furnace chamber below said pot, means for directing heat from said furnace about said pot to heat the same, an opening placing said furnace in communication with said pot to allow gravity discharge of materials from said pot into The discharge of the con-' discharge opening therein, a removable ta- 1o pered plug closing such opening, a hollow central shaft carrying scrapers, and a rod within said shaft to actuate the plug, said lug being formed to provide a sealing groove tween it and the wall of such opening in 15 I the closed position of said plug.

Signed by me, this 6 day of October, 1925.

- OTTO H. BUSE. 

